The present invention relates to electric power meters and more particularly to a device for testing the flow of electricity through an electric watt hour meter.
Utility companies frequently have watt hour meters indicating no use or less than normal use each billing period. Field personnel are dispatched to check the meters that appear to be nonoperational. Usually, a nonoperational meter is disconnected, replaced with a temporary meter, and the nonoperational meter is taken to a laboratory for testing. This necessarily disrupts service to the customer and costs the utility company for the man-hours of field and lab personnel as well as the expense of handling the accounting and billing for the customer during the disruption of service. It is known that of the meters disconnected and sent to a lab for testing, approximately 95% are actually operational and only 5% have actually stopped being functional. This knowledge indicates that considerable time and expense could be saved if apparently nonoperational meters could be checked in the field rather than being disconnected and sent to a lab for testing.
Many attempts have been made to provide field testing means without the need of removing the meter from service. Several devices incorporate a detecting means or mechanism within the meter. Unfortunately, these may be thwarted by unscrupulous consumers or may just fail, and because they are within the meter, may not be detected as the reason for no recorded consumption of power by the meter.
Another device for site testing a meter employs two clip-on transformers, one for connection about an inlet power conduit from the electric utility and the other about an inlet power supply to the consumer. Electric current measuring means determines any difference in the current sensed by the two transformers. Unfortunately, this device requires the individual power conductors to be accessible and this generally is not the case; the conductors normally being enclosed within a cable containing the return conductor. A transformer around such cable will detect zero current.
Other devices rely on magnetic flux to indicate the presence of an electric current within the meter. At least one such magnetic flux indicator (MFI) uses a mechanical analog indicator which is orientation sensitive and difficult or impossible to use on a meter located above shoulder height.
There is accordingly a need for a portable, easily used device for field testing electric watt hour meters. Such a device should be simple to learn to use and implement so that field personnel may quickly determine if an apparently nonoperational meter is actually operational.